Chillisquaque Creek is a tributary of the West Branch Susquehanna River in Montour County and Northumberland County, in Pennsylvania, in the United States. It is approximately long and flows through Derry Township, Washingtonville, and Liberty Township in Montour County and East Chillisquaque Township and West Chillisquaque Township in Northumberland County. The watershed of the creek has an area of . Agricultural impacts have caused most of the streams in the watershed of the creek (including the main stem) to be impaired. Causes of impairment include sedimentation/siltation and habitat alteration. The average annual discharge of the creek between 1980 and 2014 ranged from . Its watershed mainly consists of rolling agricultural land. The creek's channel flows through rock formations consisting of sandstone and shale. It is a warmwater stream. The watershed of Chillisquaque Creek occupies parts of four counties: Columbia County, Montour County, Northumberland County, and Lycoming County. There is a gauging station along the creek near Washingtonville. A Shawnee village had been established at the confluence with the West Branch Susquehanna River by 1728. A fort known as Fort Bosley also historically existed on the creek near Washingtonville. Numerous bridges were built over the creek in the 19th and 20th centuries, two of which are on the National Register of Historic Places. The creek is designated as a Warmwater Fishery and a Migratory Fishery. It lacks trout, but has in the past been stocked with various other fish species. A tract of the creek's floodplain is known as the Chillisquaque Creek Natural Area and is owned by Bucknell University. Various bird species have been observed near it and woodland wildflowers inhabit the creek's vicinity. Recreational opportunities in the watershed include canoeing and fishing. Course Chillisquaque Creek begins at the confluence of East Branch Chillisquaque Creek and Middle Branch Chillisquaque Creek near the northern border of Derry Township, Montour County. It flows west-southwest for a few tenths of a mile before turning south-southwest. After several tenths of a mile, it turns west for a short distance and receives the tributary West Branch Chillisquaque Creek from the right. The creek then turns south-southeast for more than a mile, flowing alongside Pennsylvania Route 54 and crossing it once. In this reach, it briefly flows alongside the western border of Washingtonville before crossing Pennsylvania Route 254 and receiving the tributary Mud Creek from the left. The creek then begins flowing in a roughly west-southwesterly